Serial Communication Converters & Adapters
Instruction Manual
10
APMA7422 RS-485 Serial
Adapter
Description
The APMA7422 converts the serial output of the
APM765/VPM3000 meter to balanced, full or half-
duplex RS-485 signals.
The APMA7422 has a removable screw terminal
connector for the 485 terminals which includes Transmit
Data (DO) and (/DO), Receive Data (DI) and (/DI), and
Signal Ground.
Baud rates are adjustable and handled by the
APM765/VPM3000 (see the Instruction Manual for
more details).
The APMA7422 has three diagnostic LEDs: a Power
(P) LED to show when the adapter is powered properly,
a Transmit Data (TX) LED to show when the adapter is
sending data out from the PC side, and a Receive Data
(RX) LED to show when the adapter is receiving data
from the APM765/VPM3000 meter.
Installation
shows the connection of a
APM765/VPM3000 meter to a PC using the APMA7422
serial adapter and a ACC1001 RS-232 to RS-485
converter in an RS-422 network. The APMA7422 has
an RJ11 connector to connect the APMA7420 modular
cable and a screw terminal connector to connect to the
RS-422 network.
several APM765/VPM3000 meters with APMA7422
serial adapters to a PC using a ACC1001 RS-232 to
RS-485 converter in an RS-485 network.
Figure 14. RS-422 or RS-485 Wiring
Notes:
1.
Termination resistors are optional and values
depend on the cable length and characteristic
impedance. Consult the cable manufacturer for
recommendations.
2.
3.
Use shielded cable, twisted-pairs plus ground.
Connect ground shield only at one location.
Figure 15. RS-485 Two-Wire Multi-Drop Wiring
Notes:
1.
Termination resistors are optional and values
depend on the cable length and characteristic
impedance. Consult the cable manufacturer for
recommendations.
2.
3.
Use shielded cable, twisted-pair plus ground.
Connect ground shield only at one location.
